The increase I use is called the Lifted Increase and goes something like this:

1. Insert your right hand needle from front to back into the top of the stitch below the next one to be knitted. Knit the stitch in the usual way.
2. Then, knit the next stitch on your left hand needle.

Repeat these two rounds, increasing four stitches per round, until you have a total of 48 stitches (24 on each needle). Or, as my emailers keep reminding me, 48 is just the sample. Increase to whatever number of stitches fits your foot as described next.

TRY IT ON. The toe should just slip over your, um, ring toe. Don’t make the mistake of increasing to fit your entire foot. Trust me on this. If it’s too small, add some more stitches. We are not assembling a Swiss watch. It’s a sock! Try it on!

Continue stockinette stitch on 48 stitches (or whatever number you have decided upon) until the sock reaches the point where your leg connects to your foot.

Begin Gusset

Decide which needle will be the gusset/heel needle.

Round 1

Gusset needle: k2, inc1, knit to second-to-last stitch, inc1, k2.

Instep needle: Knit.

Round 2

Knit

Repeat these two rounds until the heel/gusset needle contains 46 stitches. (Or two less than your total number of stitches. For 54 stitches, you would repeat until you had 52 stitches on the needle). Added in edit: there's a chart at the end of this post so you don't have to do the math.

Turn Heel

Place a marker at the center of the heel/gusset needle. You should have 23 stitches on each side (46 total).

Calculations:

23 stitches is 2 less than the total number of stitches (48) divided by 2. That is, 48-2 is the total number of stitches that will be on the Gusset needle to turn the heel.

If you are using 54 stitches, then you would have (54-2)/2=26 stitches on each side of the marker or 52 total.

SSP: Slip 2 stitches knitwise. Move them back to the LH needle and purl them together through the back loop. Or just work a P2 together if you would rather.

*Turn. Slip 1, knit back to the gap, knit the stitch before and after the gap together. Knit 1.

Turn. Slip 1, purl back to the gap, purl the stitch before and after the gap together. Purl 1.*

Repeat these two rows until you have one stitch left on each side. Then, if you haven't already done so, please see this post to avoid gusset holes.

Note that you will have two more stitches on the heel/gusset needle than you started with.

Resume knitting around both needles and decrease away the excess stitches to bring the total back to 48 stitches (or whatever your magic number of stitches is). I usually decrease 1 stitch at each end of both needles and one stitch on each side of heel center marker, which makes the heel nip in a tiny bit for the little hollow back there.

Top of Sock

As this is a generic sock pattern, you can do whatever you like.

Bind Off

I use Elizabeth Zimmerman's Sewn Cast off from Knitting Without Tears.

Break yarn, leaving a tail about 4 times as long as the circumference of the sock. Thread a tapestry needle.

* sew forward (right to left) through two stitches as if to purl, leave the stitches on. Sew backward (left to right) through one stitch as if to knit and remove the stitch.

Repeat from * until you run out of stitches. Work in tail on the inside of the sock and trim any excess.

Chart for Heel/Gusset

If your final number

of stitches is

Increase to this number of stitches for gusset for EACH side of the center marker